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Picireny Hierarchical Delta Debugging Framework

Project description

Hierarchical Delta Debugging Framework

Picireny is a Python implementation of the Hierarchical Delta Debugging (HDD in short) algorithm adapted to use ANTLR v4 for parsing both the input and the grammar(s) describing the format of the input. It relies on Picire to provide the implementation of the core Delta Debugging algorithm along with various tweaks like parallelization. Just like the Picire framework, Picireny can also be used either as a command line tool or as a library.

Both Hierarchical Delta Debugging and Delta Debugging automatically reduce “interesting” tests while keeping their “interesting” behaviour. (E.g., “interestingness” may mean failure-inducing input to a system-under-test.) However, HDD is an improvement that tries to investigate less test cases during the reduction process by making use of knowledge on the structure of the input.

The tool (and the algorithm) works iteratively in several ways. As a first step, it splits up the input into tokens and organizes them in a tree structure as defined by a grammar. Then, iteratively, it invokes Delta Debugging on each level of the tree from top to bottom, and DD is an iterative process itself, too. Finally, the nodes kept in the tree are “unparsed” to yield a reduced but still “interesting” output.


  • Python >= 3.5

  • Java SE >= 7 JRE or JDK (the latter is optional, only needed if Java is used as the parser language)


To use Picireny in another project, it can be added to setup.cfg as an install requirement (if using setuptools with declarative config):

install_requires =

To install Picireny manually, e.g., into a virtual environment, use pip:

pip install picireny

The above approaches install the latest release of Picireny from PyPI. Alternatively, for the development version, clone the project and perform a local install:

pip install .


Picireny uses the same CLI as Picire and hence accepts the same options. On top of the inherited ones, Picireny accepts several further arguments:

  • --grammar (optional): List of grammars describing the input format. (You can write them by hand or simply download them from the ANTLR v4 grammars repository.)

  • --start (optional): Name of the start rule (optionally prefixed with a grammar name) as [grammarname:]rulename.

  • --replacements (optional): Json file containing rule names and minimal replacement strings (otherwise these are calculated automatically) (see schema).

  • --format (optional): Json file describing the input format (see schema and example). This descriptor can incorporate all the above (--grammar, --start and --replacements) properties, along with the possibility of island grammar definitions. If both --format and the aforementioned arguments are present, then the latter will override the appropriate values of the format file.

  • --antlr (optional): Path to the ANTLR tool jar.

  • --parser (optional): Language of the generated parser. Currently ‘python’ (default) and ‘java’ targets (faster, but needs JDK) are supported.

Note: although, all the arguments are optional, the grammar files and the start rule of the top-level parser must be defined with an arbitrary combination of the --format, --grammars, and --start arguments.

Example usage to reduce an HTML file:

picireny --input=<path/to/the/input.html> --test=<path/to/the/tester> \
         --grammar HTMLLexer.g4 HTMLParser.g4 --start htmlDocument \
         --parallel --subset-iterator=skip --complement-iterator=backward


Picireny was tested on:

  • Linux (Ubuntu 14.04 / 16.04 / 18.04 / 20.04)

  • OS X / macOS (10.11 / 10.12 / 10.13 / 10.14 / 10.15 / 11)

  • Windows (Server 2012 R2 / Server version 1809 / Windows 10)

Acknowledgement and Citations

Picireny is motivated by the idea of Hierarchical Delta Debugging:

  • Ghassan Misherghi and Zhendong Su. HDD: Hierarchical Delta Debugging. In Proceedings of the 28th International Conference on Software Engineering (ICSE ‘06), pages 142-151, Shanghai, China, May 2006. ACM.

The details of the modernized re-implementation and further improvements are published in:

  • Renata Hodovan and Akos Kiss. Modernizing Hierarchical Delta Debugging. In Proceedings of the 7th International Workshop on Automating Test Case Design, Selection, and Evaluation (A-TEST 2016), pages 31-37, Seattle, Washington, USA, November 2016. ACM.

  • Renata Hodovan, Akos Kiss, and Tibor Gyimothy. Tree Preprocessing and Test Outcome Caching for Efficient Hierarchical Delta Debugging. In Proceedings of the 12th IEEE/ACM International Workshop on Automation of Software Testing (AST 2017), pages 23-29, Buenos Aires, Argentina, May 2017. IEEE.

  • Renata Hodovan, Akos Kiss, and Tibor Gyimothy. Coarse Hierarchical Delta Debugging. In Proceedings of the 33rd IEEE International Conference on Software Maintenance and Evolution (ICSME 2017), pages 194-203, Shanghai, China, September 2017. IEEE.

  • Akos Kiss, Renata Hodovan, and Tibor Gyimothy. HDDr: A Recursive Variant of the Hierarchical Delta Debugging Algorithm. In Proceedings of the 9th ACM SIGSOFT International Workshop on Automating Test Case Design, Selection, and Evaluation (A-TEST 2018), pages 16-22, Lake Buena Vista, Florida, USA, November 2018. ACM.

  • Daniel Vince, Renata Hodovan, Daniella Barsony, and Akos Kiss. Extending Hierarchical Delta Debugging with Hoisting. In Proceedings of the 2nd ACM/IEEE International Conference on Automation of Software Test (AST 2021), pages 60-69, Madrid, Spain (Virtual), May 2021. IEEE.

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